<?php

namespace PHPExcel\CachedObjectStorage;

/**
 * PHPExcel_CachedObjectStorage_Memcache
 *
 * Copyright (c) 2006 - 2015 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * @category PHPExcel
 * @package PHPExcel_CachedObjectStorage
 * @copyright Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt LGPL
 * @version ##VERSION##, ##DATE##
 */
class Memcache extends CacheBase implements ICache {
    /**
     * Prefix used to uniquely identify cache data for this worksheet
     *
     * @var string
     */
    private $cachePrefix = null;
    
    /**
     * Cache timeout
     *
     * @var integer
     */
    private $cacheTime = 600;
    
    /**
     * Memcache interface
     *
     * @var resource
     */
    private $memcache = null;
    
    /**
     * Store cell data in cache for the current cell object if it's "dirty",
     * and the 'nullify' the current cell object
     *
     * @throws \PHPExcel\Exception
     */
    protected function storeData() {
        if ($this->currentCellIsDirty && !empty($this->currentObjectID)) {
            $this->currentObject->detach();
            
            $obj = serialize($this->currentObject);
            if (!$this->memcache->replace($this->cachePrefix . $this->currentObjectID . '.cache', $obj, null, $this->cacheTime)) {
                if (!$this->memcache->add($this->cachePrefix . $this->currentObjectID . '.cache', $obj, null, $this->cacheTime)) {
                    $this->__destruct();
                    throw new \PHPExcel\Exception("Failed to store cell {$this->currentObjectID} in MemCache");
                }
            }
            $this->currentCellIsDirty = false;
        }
        $this->currentObjectID = $this->currentObject = null;
    }
    
    /**
     * Add or Update a cell in cache identified by coordinate address
     *
     * @param string $pCoord
     *            Coordinate address of the cell to update
     * @param \PHPExcel\Cell $cell
     *            Cell to update
     * @return \PHPExcel\Cell
     * @throws \PHPExcel\Exception
     */
    public function addCacheData($pCoord, \PHPExcel\Cell $cell) {
        if (($pCoord !== $this->currentObjectID) && ($this->currentObjectID !== null)) {
            $this->storeData();
        }
        $this->cellCache[$pCoord] = true;
        
        $this->currentObjectID = $pCoord;
        $this->currentObject = $cell;
        $this->currentCellIsDirty = true;
        
        return $cell;
    }
    
    /**
     * Is a value set in the current \PHPExcel\CachedObjectStorage\ICache for an indexed cell?
     *
     * @param string $pCoord
     *            Coordinate address of the cell to check
     * @return boolean
     * @throws \PHPExcel\Exception
     */
    public function isDataSet($pCoord) {
        // Check if the requested entry is the current object, or exists in the cache
        if (parent::isDataSet($pCoord)) {
            if ($this->currentObjectID == $pCoord) {
                return true;
            }
            // Check if the requested entry still exists in Memcache
            $success = $this->memcache->get($this->cachePrefix . $pCoord . '.cache');
            if ($success === false) {
                // Entry no longer exists in Memcache, so clear it from the cache array
                parent::deleteCacheData($pCoord);
                throw new \PHPExcel\Exception('Cell entry ' . $pCoord . ' no longer exists in MemCache');
            }
            return true;
        }
        return false;
    }
    
    /**
     * Get cell at a specific coordinate
     *
     * @param string $pCoord
     *            Coordinate of the cell
     * @throws \PHPExcel\Exception
     * @return \PHPExcel\Cell Cell that was found, or null if not found
     */
    public function getCacheData($pCoord) {
        if ($pCoord === $this->currentObjectID) {
            return $this->currentObject;
        }
        $this->storeData();
        
        // Check if the entry that has been requested actually exists
        if (parent::isDataSet($pCoord)) {
            $obj = $this->memcache->get($this->cachePrefix . $pCoord . '.cache');
            if ($obj === false) {
                // Entry no longer exists in Memcache, so clear it from the cache array
                parent::deleteCacheData($pCoord);
                throw new \PHPExcel\Exception("Cell entry {$pCoord} no longer exists in MemCache");
            }
        } else {
            // Return null if requested entry doesn't exist in cache
            return null;
        }
        
        // Set current entry to the requested entry
        $this->currentObjectID = $pCoord;
        $this->currentObject = unserialize($obj);
        // Re-attach this as the cell's parent
        $this->currentObject->attach($this);
        
        // Return requested entry
        return $this->currentObject;
    }
    
    /**
     * Get a list of all cell addresses currently held in cache
     *
     * @return string[]
     */
    public function getCellList() {
        if ($this->currentObjectID !== null) {
            $this->storeData();
        }
        
        return parent::getCellList();
    }
    
    /**
     * Delete a cell in cache identified by coordinate address
     *
     * @param string $pCoord
     *            Coordinate address of the cell to delete
     * @throws \PHPExcel\Exception
     */
    public function deleteCacheData($pCoord) {
        // Delete the entry from Memcache
        $this->memcache->delete($this->cachePrefix . $pCoord . '.cache');
        
        // Delete the entry from our cell address array
        parent::deleteCacheData($pCoord);
    }
    
    /**
     * Clone the cell collection
     *
     * @param \PHPExcel\Worksheet $parent
     *            The new worksheet that we're copying to
     * @throws \PHPExcel\Exception
     */
    public function copyCellCollection(\PHPExcel\Worksheet $parent) {
        parent::copyCellCollection($parent);
        // Get a new id for the new file name
        $baseUnique = $this->getUniqueID();
        $newCachePrefix = substr(md5($baseUnique), 0, 8) . '.';
        $cacheList = $this->getCellList();
        foreach ( $cacheList as $cellID ) {
            if ($cellID != $this->currentObjectID) {
                $obj = $this->memcache->get($this->cachePrefix . $cellID . '.cache');
                if ($obj === false) {
                    // Entry no longer exists in Memcache, so clear it from the cache array
                    parent::deleteCacheData($cellID);
                    throw new \PHPExcel\Exception("Cell entry {$cellID} no longer exists in MemCache");
                }
                if (!$this->memcache->add($newCachePrefix . $cellID . '.cache', $obj, null, $this->cacheTime)) {
                    $this->__destruct();
                    throw new \PHPExcel\Exception("Failed to store cell {$cellID} in MemCache");
                }
            }
        }
        $this->cachePrefix = $newCachePrefix;
    }
    
    /**
     * Clear the cell collection and disconnect from our parent
     *
     * @return void
     */
    public function unsetWorksheetCells() {
        if (!is_null($this->currentObject)) {
            $this->currentObject->detach();
            $this->currentObject = $this->currentObjectID = null;
        }
        
        // Flush the Memcache cache
        $this->__destruct();
        
        $this->cellCache = array();
        
        // detach ourself from the worksheet, so that it can then delete this object successfully
        $this->parent = null;
    }
    
    /**
     * Initialise this new cell collection
     *
     * @param \PHPExcel\Worksheet $parent
     *            The worksheet for this cell collection
     * @param mixed[] $arguments
     *            Additional initialisation arguments
     * @throws \PHPExcel\Exception
     */
    public function __construct(\PHPExcel\Worksheet $parent, $arguments) {
        $memcacheServer = (isset($arguments['memcacheServer'])) ? $arguments['memcacheServer'] : 'localhost';
        $memcachePort = (isset($arguments['memcachePort'])) ? $arguments['memcachePort'] : 11211;
        $cacheTime = (isset($arguments['cacheTime'])) ? $arguments['cacheTime'] : 600;
        
        if (is_null($this->cachePrefix)) {
            $baseUnique = $this->getUniqueID();
            $this->cachePrefix = substr(md5($baseUnique), 0, 8) . '.';
            
            // Set a new Memcache object and connect to the Memcache server
            $this->memcache = new Memcache();
            if (!$this->memcache->addServer($memcacheServer, $memcachePort, false, 50, 5, 5, true, array(
            $this,
            'failureCallback' 
            ))) {
                throw new \PHPExcel\Exception("Could not connect to MemCache server at {$memcacheServer}:{$memcachePort}");
            }
            $this->cacheTime = $cacheTime;
            
            parent::__construct($parent);
        }
    }
    
    /**
     * Memcache error handler
     *
     * @param string $host
     *            Memcache server
     * @param integer $port
     *            Memcache port
     * @throws \PHPExcel\Exception
     */
    public function failureCallback($host, $port) {
        throw new \PHPExcel\Exception("memcache {$host}:{$port} failed");
    }
    
    /**
     * Destroy this cell collection
     */
    public function __destruct() {
        $cacheList = $this->getCellList();
        foreach ( $cacheList as $cellID ) {
            $this->memcache->delete($this->cachePrefix . $cellID . '.cache');
        }
    }
    
    /**
     * Identify whether the caching method is currently available
     * Some methods are dependent on the availability of certain extensions being enabled in the PHP build
     *
     * @return boolean
     */
    public static function cacheMethodIsAvailable() {
        if (!function_exists('memcache_add')) {
            return false;
        }
        
        return true;
    }
}
